Conventionally, in order to obtain a moisture-permeable waterproof composite material which is excellent in moisture permeability and waterproofness, some methods have been taken such as introducing a hydrophilic part into a polymer chain or blending hydrophilic resin in a hydrophobic resin. In any cases, various methods have been investigated by modifying or blending organic solvent type resin (for example, refer to JP-A-1995-9631, JP-A-1995-3147).
In recent years, VOC (Volatile Organic Compounds) regulation has become enforceable in consideration of earth environment, and it has been desired to change resin solvent from organic solvent to aqueous solvent. Use of a hydrophilic resin in the field of moisture-permeable waterproof composite material has been partly tried (for example, refer to JP-A-1989-97272 and JP-A-1989-97274). However, there is still no technique in which moisture permeability and waterproofness are compatible like those in which organic solvent type resin is used and no technique which can be practically used has not been found out with the present technique. Furthermore, there is no technique having material durability together with practical performance.
In case of aqueous resin, by introducing hydrophilic-part in polymer chain in non-aqueous resin or by blending high moisture-permeable hydrophilic resin into low moisture-permeable resin, it has been very difficult to satisfy both of material performance and material durability because of remarkable decrease of film strength.
This invention, having regard to the above-mentioned present situation, provides a moisture-permeable, waterproof film and a composite material which can be manufactured by an ecological process, by utilizing a polymer with an excellent moisture permeability, waterproofness, material durability and capability of being made aqueous.